regression on -current with pyparsing and python-markdown

in SFS, I'm stuck by a circular dependency between:
- pyparsing
- python-mardown
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1st order: pyparsing then python-markdown
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self.require(*args, **kwargs)
File "/usr/lib64/python3.9/site-packages/pkg_resources/__init__.py", line 2472, in require
items = working_set.resolve(reqs, env, installer, extras=self.extras)
File "/usr/lib64/python3.9/site-packages/pkg_resources/__init__.py", line 772, in resolve
raise DistributionNotFound(req, requirers)
pkg_resources.DistributionNotFound: The 'pyparsing<3,>=2.0.2' distribution was not found and is required by packaging
------------------
2nd order: python-markdown then pyparsing
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File "/usr/lib64/python3.9/site-packages/pkg_resources/__init__.py", line 2472, in require
items = working_set.resolve(reqs, env, installer, extras=self.extras)
File "/usr/lib64/python3.9/site-packages/pkg_resources/__init__.py", line 772, in resolve
raise DistributionNotFound(req, requirers)
pkg_resources.DistributionNotFound: The 'packaging>=20.0' distribution was not found and is required by the application
------------------
same problem in Slackware, if you remove the 2 packages, they can't be built anymore.
Any idea?